2018 marks the 20th anniversary of Steven Spielberg's Saving Private Ryan, an iconic film that remains one of the most honest depictions of war.

"It was a mentally demoralizing experience for us," Spielberg told film critic Roger Ebert. Nevertheless, it was important for the director "to show America the dark side of the face of war."

Director Steven Spielberg on set during the filming of 'Saving Private Ryan.'(Photo by DreamWorks Studios and Paramount Pictures)

Spielberg made many deliberate decisions to ensure the authenticity and the truth of war portrayed in this film, and the behind-the-scenes footage is riveting. The D-Day invasion scene took over two weeks to shoot and involved thousands of extras — including Irish Army reservists and real amputees.

Even the camera movements and lenses were all designed to follow the movement of combat and obscure the viewer's vision, replicating the chaos and confusion of battle. Spielberg shot the film chronologically, which is an unusual choice for filmmakers.

"We shot in continuity, from beginning to end. We were all reliving the story together...but I didn't realize how devastating that was going to be for the whole cast to actually start off with Omaha Beach and survive that as a film team, and then move into the hedgerows, move into the next town, as we all began to get whittled down by the storytelling."

It was important for Spielberg to honor those who fought in World War II. "I think it is the key — the turning point of the entire century. World War II allowed my generation to exist." His own father, Arnold Spielberg, enlisted in the U.S. Army after the attacks against Pearl Harbor.